Asipov Leonid

L-Data Research          

Introduction

In this short article we’ll try to answer how the physical parameters photosynthesis and transpiration correlate with illumination levels.

Photosynthesis and transpiration correlation with illumination levels

Generally, photosynthesis is positively correlated with light, with saturation at higher light levels.

Transpiration is also positively correlated with light, with slower response rates.

Figure 1: Photosynthesis and transpiration at changing light levels in controlled room

Figure 2: Photosynthesis and transpiration at changing light levels in natural light

As we see, in natural light conditions, there are many fluctuations in the light levels. Photosynthesis and transpiration are induced similarly to the light fluctuations, while transpiration responds more slowly. The slower response of the transpiration rate to changes in the illumination levels is seen as well in controlled light conditions (figure 1).

Does each leaf responds to light independently, or is the response is on the level of the whole plant?

To answer that, we measured photosynthesis on the level of a single leaf in a confined chamber with controlled light conditions. 

Figure 3: Experimental setup

First, we turn the light in the measurement chamber, while the outer light is on. Then, after a period of time we turn off the outer light. We see that photosynthesis stops after the light is off in the chamber. Rest of the plant is illuminated, but it has no effect on the photosynthesis of the leaf in the chamber.

Figure 2: Leaves light responses are independent of one another

We make another experiment, in which we first turn off the light outside, while the leaf in the chamber is illuminated. After a period of time, the light inside the chamber is turned off as well. We see that the leaf in the chamber continue photosynthesizing despite the darkness outside the chamber.

Figure 3: Leaves light responses are independent of one another

Conclusions

Leaves respond to light independently of one another, according to the conditions surrounding each leaf. They may be considered as separate photosynthetic units. Most likely there is no central control over the response of plants to light and the response is conducted on the level of single cells.

Materials and Methods

Photosynthesis and transpiration was measured with Li-Cor LI6400 portable photosynthesis system.

The data was analyzed with Data-Lightning 0.1 visual data analysis platform by L-Data, Israel

http://www.ldata.co.il

The plants were wt Solanum lycopersicum (Tomato) of 30 days from germination.

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